The present invention relates to an improved CCD image sensor and manufacturing method therefor.
FIG. 1 is a sectional view showing a conventional CCD image sensor. Here, a plurality of photoelectric conversion devices 1, i.e., photodiodes, are formed on a substrate while being spaced from one another by a predetermined distance, and a plurality of vertical charge coupled devices (hereinafter referred to as "VCCDs") 2 are formed between the photodiodes 1. A lower planarizing layer 3 is formed to allow the photodiodes 1 and VCCDs 2 to have a flat surface throughout the whole structure, and dye layers 4a, 4b and 4c are respectively formed on corresponding places on the lower planarizing layer 3. An upper planarizing layer 5 is formed on the dye layers 4a, 4b and 4c and exposed lower planarizing layer 3 to planarize overall surface of the resultant structure. Also, a plurality of hemispheric micro-lenses 6 are formed on the upper planarizing layer 5. A reference numeral 7 denotes a pad for dividing respective cells.
Typically, in the CCD image sensor, the lower planarizing layer 3 is coated on the photodiodes 1 and VCCDs 2, and, successively, the dye layers 4a, 4b and 4c are formed on the lower planarizing layer 3. At this time, the dye layers 4a, 4b and 4c are differently shaped from one another to make the whole surface uneven with the consequence of necessarily forming the upper planarizing layer 5 thereon.
Therefore, during the manufacturing of the CCD image sensor, since the height from the photodiodes 1 to the micro-lenses 6 is thickened, there is a problem that overall light transmissivity is degraded. Furthermore, due to the thick layer, it is apt to result in light loss or divergence when the light incident to the micro-lenses 6 is focused onto the photodiodes 1. In addition, the focusing rate thereof may be lowered owing to a scattering phenomenon of light.